Abstract: This paper introduces the UNIFAC group contribution approach into Butlers equation. A new method is set up to predict the surface tension of binary and multicomponent non-electrolyte systems, requiring only pure component properties and UNIFAC parameters. With the introduction of the activity coefficients γBi=αBi/xBi, γSi=αSi/xSi, Butlers equation may be transformed to give Here σm represents the surface tension of the mixture and σi the surface tension of pure component i. Ai is the molar surface area of component i and Ai its partial molar surface area in the solution, αBi, γBi and xBi stand for the activity, the activity coefficient and molar fraction of component i in the bulk liquid respectively and αSi, γSi and xSi for those 011 the surface layer of solution. N is the number of components. The value of Ai is set up equal to Ai which is calculated from the equation Ai=Vi2/3N01/3 where Vi is the liquid molar volume of pure component i and N0 Avogadros number. The bulk activity coefficients and surface activity coefficients are calculated with UNIFAC group contribution approach in a similar way. Predictions based on this approach agree well with experimental data for 100 binary, 10 ternary and 2 quaternary systems. The total average relative deviations from experiment are 2.53% and 5.33% for binary and multicomponent systems respectively, within acceptable limit for engineering design.

摘要： 本文将Butler方程与UNIFAC模型相结合,建立了一个仅需纯液体摩尔体积V_i、表面张力σ_i和UNIFAC基团参数便能推算二元和多元液体混合物表面张力的新方法.用此法对100个二元体系、10个三元体系和2个四元体系的表面张力做了推算,二元和多元体系的总平均相对偏差相应为2.53%和5.33%,表明计算方法可靠,推算精度能满足工程设计要求.